Chinese Researchers Update Lunar Chronology Model
The photo shows the sampling sites on the lunar surface. (Provided by the Aerospace Information Research Institute, Chinese Academy of Sciences)
BEIJING, Feb. 17 (Xinhua) -- Chinese researchers have updated the most widely used chronology model to provide more accurate time scales for lunar and planetary research.
Lunar chronology models were built by associating the radiometric ages of samples returned by the Apollo and Luna missions measured in the laboratory with compiled crater distributions of those sites, according to a research article recently published in the journal Nature Astronomy.
Such models have been widely used to determine the absolute ages of various regions on the Moon, as well as been generalized to date the surfaces of the rocky bodies of the inner Solar System.
However, there is a gap in previous sample ages between three billion years and one billion years ago, which occupies almost half of the history of the Moon.
The Chang'e-5 probe brought back basalt material from a young mare area that has been radiometrically dated to the center of this gap at about two billion years old.
Based on the analysis of crater size-frequency distribution, the researchers from the Aerospace Information Research Institute under the Chinese Academy of Sciences updated the Neukum model (1983) and established the new lunar chronology model.
They found that the updated model is consistent with a combination of an exponential decrease and a linear rate. Compared with the old chronology model, the new model gives older ages in most cases, with a maximum difference of about 200 million years.
The results have important implications for the chronology and impact history of the inner solar system.
Furthermore, the updated lunar chronology model is expected to refine the chronology models of rocky planets such as Mars and Mercury with high accuracy.